Readout circuit for uncooled infrared focal plane array

Abstract

A readout circuit for an uncooled infrared focal plane array includes: a first biasing circuit for generating a detection output signal; a second biasing circuit for generating a first reference output signal; a first integration circuit; and an analog-to-digital circuit including: a ramp signal generating circuit for generating a ramp signal according to a second reference microbolometer of a third biasing circuit. In the readout circuit, subtracting and amplifying the detection output signal and the first reference output signal are provided by the integrator at an analog domain, while ratio counting is provided by an analog-to-digital converter during analog-to-digital conversion. Furthermore, a column level integrated readout channel utilizes only one reference microbolometer, and the chip level ramp signal generator also utilizes only one reference microbolometer. Therefore, a chip area is further saved, and noise sources are decreased.

Description

CROSS REFERENCE OF RELATED APPLICATION[0001]The present invention claims priority under 35 U.S.C. 119(a-d) to CN 201410008992.2, filed Jan. 9, 2014.BACKGROUND OF THE PRESENT INVENTION[0002]1. Field of Invention[0003]The present invention relates to a technique field of infrared focal plane arrays, and more particularly to a readout circuit for an uncooled infrared focal plane array.[0004]2. Description of Related Arts[0005]If a microbolometer infrared imaging system, as one kind of thermal infrared detector, is not compensated by special methods, a detection result thereof is associated with the substrate temperature. In practice, infrared detection results are expected to be only associated with the temperature of the object, and independent of other factors.[0006]The thermo-electric cooler (TEC for short) utilized in the conventional uncooled microbolometer infrared imaging system compensates the substrate temperature. However, TEC has a certain volume and power consumption, which...

AI Technical Summary

Benefits of technology

The present invention provides a readout circuit for an uncooled infrared focal plane array with high dynamic range, smaller chip area, and lower power consumption compared to conventional products. The readout circuit achieves substrate temperature compensation by the analog-to-digital conversion, which reduces noise introduced compared to conventional ways. The column level integrated readout channel and chip level ramp signal generator utilize only one reference microbolometer, which saves chip area and decreases noise sources.

Problems solved by technology

However, TEC has a certain volume and power consumption, which limits the application of uncooled infrared focal plane array detector.

However, in the microbolometer infrared imaging system without TEC, non-ideal effects such as extreme non-uniformity and non-linearity of the focal plane array will be caused by the change of the substrate temperature, thereby affecting a readout result.

However, these output digital signals are substrate temperature dependent.

The drawback of this method is the dramatic decrease of scene dynamic range.

As a result, the chip area and power consumption will be increased.

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